A related-art concealed slide fastener includes a pair of fastener tapes, a pair of fastener element rows, a slider, a box pin and a box body, an insert pin. The pair of fastener element rows are respectively provided on bent edges which are formed by bending opposing tape side edges of the pair of fastener tapes along a longitudinal direction thereof into substantially U-shape. Each of the fastener element rows has a plurality of fastener elements. The slider is configured to insert the pair of fastener element rows therethrough and configured to engage and disengaged the pair of fastener element rows with and from each other. The box pin and the box body are provided at one end of one of the pair of fastener tapes in a longitudinal direction of the fastener element rows. The insert pin is provided at one end of another of the pair of fastener tapes in the longitudinal direction of the pair of fastener element rows. The insert pin can be inserted into the box body. An engagement portion configured to be engaged with the lowermost fastener element of the fastener element row which is close to the box pin is formed on a side surface of the insert pin, which faces the box pin. The related-art concealed slide fastener prevents the slide fastener from being opened from a side of a separable end stop (the box pin, the box body and the insert pin) when lateral pulling force is applied to the slide fastener (e.g., refer to Patent Document 1).